Evaluation on blood platelets by the image analysis system VIDAS 2.5.

This paper introduces a program written on the image analysis system VIDAS 2.5. It enables the automatic quantification of high numbers of adhesion areas of vital human platelets, thus allowing statistical analysis. These adhesion areas were observed by reflection contrast microscopy (RCM), which generates images of an intense contrast and serves as a prerequisite for an evaluation by image analysis. However, RCM-photographs of the observed platelets have highly varying mean greyvalues and greyranges. These common problems for self-operating identification are excluded by two procedures within the program: 1. calibration of the scanning process for an optimal use of the available greyvalues provided by the negative, camera, and the image analysis system; and 2. relation of the threshold for discrimination of adhesion areas to the statistic parameters of the histogram within each individual digitized image. Images processed according to these prerequisites were transferred to the VIDAS implemented routines for identification and measurement of areas. Thus, image analysis combined with RCM offers a tool for basic and clinical platelet research, which is shown by an example of stimulation and inhibited stimulation of platelet activation.